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Eat, Drink and Be Healthy

Adults can have allergic reactions, too

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By Jennifer Huget
Thursday, October 22, 2009

When D.C. Council member Marion Barry swelled up after eating shrimp-and-crab soup last week, he abruptly joined the ranks of an estimated 12 million people in the United States with food allergies.

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We're so accustomed to hearing about kids who can't eat peanuts that we tend to forget about grown-ups who are allergic to certain foods. In fact, only a quarter of those with food allergies are kids. And though children tend to be allergic to milk, eggs, soy and wheat in addition to peanuts and tree nuts -- allergies they sometimes outgrow -- shellfish allergies such as Barry's are the most common food allergy affecting adults and among the most likely to strike otherwise healthy adults out of the blue. Unfortunately, they're also among the most dangerous, likely to set serious reactions in motion within moments. And unlike kids, adults are unlikely to outgrow their allergies.

According to an account in The Post, Barry, 73, suffered a fairly typical allergic reaction to his shellfish-studded soup: He felt his throat begin to swell shut, his vision blur and his tongue go numb. His companions did the right thing by rushing him to an emergency room, where he was treated and released, with an order to avoid shellfish from now on. The former D.C. mayor reportedly had never had such a reaction to shellfish.

Food allergies are the body's immune response to foods containing proteins that it perceives as foreign intruders. Hives, swelling, strange feelings in the throat and trouble breathing characterize the classic allergic response. When swelling gets out of control, it can obstruct breathing and lead to death. Although mild reactions can be treated with antihistamines such as Benadryl, more-severe ones require immediate medical attention.

Scott H. Sicherer, an associate professor of pediatrics at the Mount Sinai School of Medicine and medical adviser to the New York-based Food Allergy Initiative, advises people who have had a first allergic reaction to get that medical help right away. "Don't just go home and take a bath," he says, "because it might get worse. If your reaction is severe, call 911 or get to the emergency room."

When things have settled down, he says, you should see an allergist to establish whether you in fact have an allergy and to pin down what you're allergic to. "You should confirm the diagnosis so you're avoiding the food you need to avoid," Sicherer says. An allergist can offer guidance in avoiding that food, too, a "big, life-changing" task that he says "can be very tricky."

In addition to strict avoidance of the offending food, of which even trace amounts can cause trouble, people with food allergies should carry an EpiPen or other auto-injector that administers epinephrine, a hormone that helps open airways, in case of inadvertent exposure.

Sicherer says a recent study found that one in 50 people answering a survey reported having had an allergic reaction to shellfish or fish. He adds that having such a reaction occur for the first time as an adult is not atypical. But, he says, "the $64,000 question is 'Why?' "

"Something has to have changed" in the person's immune system, he says. We just don't know what.

According to Robert Wood, chief of pediatric allergy and immunology at Johns Hopkins Children's Center and author of "Food Allergies for Dummies" (and a peanut-allergic adult), we have one tantalizing clue: Many people who are allergic to shellfish are also allergic to dust mites or cockroaches, which have in common with shellfish a protein called tropomyosin. But the connection is so tenuous that Wood does not recommend people with dust mite or cockroach allergies avoid shellfish.

The Food Allergy Initiative reports that researchers at Mount Sinai are working to create substances that mimic the offending shellfish antigens in hopes of using them to develop vaccines (along the lines of allergy shots for hay fever) for food allergies. Five such allergens have been identified and cloned, but a vaccine remains a distant prospect.

Despite a recent uptick in research that Wood predicts will within 20 years make food allergies more manageable, if not preventable, treatment for food allergies -- such as avoiding the trigger food and getting medication if you're accidentally exposed -- "has not evolved much at all," he says. "It's the same as it has been for a hundred years."



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